Uploaded patch for suggested solution to this problem: Validated on Mac OS X 10.5 and Linux. Interestingly, on Linux:

checking whether ld understands -no_compact_unwind... yes

Although not ideal, this is currently harmless, at least given the conditions on -no_compact_unwind use in compiler/main/DriverPipeline.hs. And please note: I have not had the opportunity to test this under circumstances where -no_compact_unwind actually should be used.